! C06FFF Example Program Text
! Mark 30.1 Release. NAG Copyright 2024.
Module c06fffe_mod
! C06FFF Example Program Module:
! Parameters and User-defined Routines
! .. Use Statements ..
Use nag_library, Only: nag_wp
! .. Implicit None Statement ..
Implicit None
! .. Accessibility Statements ..
Private
Public :: readxy, writxy
! .. Parameters ..
Integer, Parameter, Public :: nin = 5, nout = 6
Contains
Subroutine readxy(nin,x,y,n1,n2)
! Read 2-dimensional complex data
! .. Scalar Arguments ..
Integer, Intent (In) :: n1, n2, nin
! .. Array Arguments ..
Real (Kind=nag_wp), Intent (Out) :: x(n1,n2), y(n1,n2)
! .. Local Scalars ..
Integer :: i, j
! .. Executable Statements ..
Do i = 1, n1
Read (nin,*)(x(i,j),j=1,n2)
Read (nin,*)(y(i,j),j=1,n2)
End Do
Return
End Subroutine readxy
Subroutine writxy(nout,x,y,n1,n2)
! Print 2-dimensional complex data
! .. Scalar Arguments ..
Integer, Intent (In) :: n1, n2, nout
! .. Array Arguments ..
Real (Kind=nag_wp), Intent (In) :: x(n1,n2), y(n1,n2)
! .. Local Scalars ..
Integer :: i, j
! .. Executable Statements ..
Do i = 1, n1
Write (nout,*)
Write (nout,99999) 'Real ', (x(i,j),j=1,n2)
Write (nout,99999) 'Imag ', (y(i,j),j=1,n2)
End Do
Return
99999 Format (1X,A,7F10.3,/,(6X,7F10.3))
End Subroutine writxy
End Module c06fffe_mod
Program c06fffe
! C06FFF Example Main Program
! .. Use Statements ..
Use c06fffe_mod, Only: nin, nout, readxy, writxy
Use nag_library, Only: c06fff, nag_wp
! .. Implicit None Statement ..
Implicit None
! .. Local Scalars ..
Integer :: ieof, ifail, l, lwork, n, ndim
! .. Local Arrays ..
Real (Kind=nag_wp), Allocatable :: work(:), x(:), y(:)
Integer, Allocatable :: nd(:)
! .. Intrinsic Procedures ..
Intrinsic :: product
! .. Executable Statements ..
Write (nout,*) 'C06FFF Example Program Results'
! Skip heading in data file
Read (nin,*)
loop: Do
Read (nin,*,Iostat=ieof) ndim
If (ieof<0) Then
Exit loop
End If
Allocate (nd(ndim))
Read (nin,*) nd(1:ndim), l
n = product(nd(1:ndim))
lwork = 3*nd(l)
Allocate (x(n),y(n),work(lwork))
Call readxy(nin,x,y,nd(1),nd(2))
Write (nout,*)
Write (nout,*) 'Original data'
Call writxy(nout,x,y,nd(1),nd(2))
! ifail: behaviour on error exit
! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
! Compute transform
ifail = 0
Call c06fff(ndim,l,nd,n,x,y,work,lwork,ifail)
Write (nout,*)
Write (nout,99999) 'Discrete Fourier transform of variable ', l
Call writxy(nout,x,y,nd(1),nd(2))
! Compute inverse transform
y(1:n) = -y(1:n)
Call c06fff(ndim,l,nd,n,x,y,work,lwork,ifail)
y(1:n) = -y(1:n)
Write (nout,*)
Write (nout,*) 'Original sequence as restored by inverse transform'
Call writxy(nout,x,y,nd(1),nd(2))
Deallocate (x,y,work,nd)
End Do loop
99999 Format (1X,A,I1)
End Program c06fffe